The medical term for left posterior branch block is really relatively new to the average person, because many people do not pay special attention to this disease, but sometimes it is a little careless. Complications may be so severe that they endanger the patient’s illness, so we must pay attention to them. · What is the left posterior branch block? Left posterior branch conduction block is often called left posterior half block. The left posterior branch block itself has no obvious symptoms. If it is combined with the right bundle branch block, it will cause symptoms such as syncope and convulsions. According to the diagnostic characteristics of the ECG of the left posterior branch block, the QRS wave ECG axis is about 120 °, which is of type SⅠQⅢ, and the QRS wave time limit does not exceed 0.10s, excluding other causes that can cause a significant right deviation of the electrical axis, and continuous dynamic observation of the ECG Changes can be diagnosed. Simple left posterior branch block is rare, but it can form double bundle branch block or triple bundle branch block with right bundle branch, left anterior branch or septal branch block, so special attention should be paid to diagnosis Identification, to avoid missed diagnosis, in addition can also be based on ECG vector diagnostic criteria. · The causes and mechanisms of left posterior branch block ①The causes of left posterior branch block The common causes of left posterior branch block are coronary heart disease, the incidence of myocardial infarction is about 1%, because of the need Multi-vessel occlusion leads to anterior wall combined with inferior wall and right ventricular infarction, or anterior descending branch disease leads to extensive ischemia and necrosis of the ventricular septum, and rarely occurs alone. Others include hypertension, cardiomyopathy, myocarditis, aortic valve disease or degenerative changes of the indoor conduction system, dissecting aneurysms, acute pulmonary heart disease, aortic arch narrowing, and hyperkalemia. It can also be found in healthy people. ②Left posterior branch block pathogenesis Left posterior branch block is less common than left anterior branch block. Because the left posterior branch is short and thick, about 20 mm long and about 6 mm thick, the blood supply comes from the left circumflex branch of the left coronary artery and the right coronary artery, and there is a double blood supply. The left posterior branch is located in the left ventricle that is not vulnerable to invasion The inflow channel is lightly impacted by blood flow. Once a conduction block appears in the left posterior branch, it often indicates a more extensive and severe lesion. It also indicates that there is pre-existing or simultaneous conduction damage to the right bundle branch or the left front branch. Blocking of the left posterior branch alone is rare. Through some understanding of the above left posterior branch block symptoms, if we can detect and pay attention to it early, we can actually avoid many dangers, so the key to protecting our own health is to know that it is dangerous to our lives and health Some things.